With his recent appearance on Doctor Who, Mark Sheppard cemented his place as science fiction's greatest character actor. But we've been loving Sheppard for years...and we assembled this video of every last one of his scifi roles to prove his awesomeness.

This covers the greatest Sheppard moments, from his recent appearances on Warehouse 13 and Supernatural to his early work on The X-Files and Star Trek: Voyager. It's eighteen years worth of larger-than-life performances, snarky banter, and moral ambiguity, complete with at least a half-dozen different accents, multiple threats of bodily harm, and a couple of the most ridiculous face prosthetics we've ever seen.

We only had two ground rules here - we stuck to his TV show appearances, and the TV shows had to have some science fiction or supernatural element. So no Burn Notice, no Leverage, no 24, and, sadly, no Megalodon. But that still left us plenty to work with, as you can see in the finished video.

Here's the complete list of shows included in chronological order: The X-Files, M.A.N.T.I.S., Sliders, Star Trek: Voyager, The Invisible Man, The Chronicle, Special Unit 2, Charmed, Firefly, Jake 2.0, Medium, Battlestar Galactica, Bionic Woman, The Middleman, Dollhouse, Warehouse 13, Chuck, Supernatural, and Doctor Who. For shows where he's appeared over multiple seasons like BSG or Supernatural, we just used the year from the clip in question.